CN115669170A - Multiple starting points related to Channel Occupancy Time (COT) for sidelink communications - Google Patents

Abstract

Wireless communication systems and methods related to communicating sidelink communications among sidelink user equipment devices (UEs) are provided. The UE may determine a first starting point from a plurality of starting points and perform Listen Before Talk (LBT) to contend for a Channel Occupancy Time (COT) starting at the first starting point. The UE may transmit a sidelink communication beginning at a first starting point during the COT based on the LBT.

Description

Multiple starting points related to Channel Occupancy Time (COT) for sidelink communications

Technical Field

The present application relates to wireless communication systems, and more particularly, to multiple starting points for Channel Occupancy Time (COT) for sidelink communications between user equipment devices (UEs).

Introduction to the design reside in

Wireless communication systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be capable of supporting communication with multiple users by sharing the available system resources (e.g., time, frequency, and power). A wireless multiple-access communication system may include several Base Stations (BSs), each supporting communication for multiple communication devices simultaneously, which may otherwise be referred to as User Equipment (UE).

To meet the growing demand for extended mobile broadband connectivity, wireless communication technologies are advancing from Long Term Evolution (LTE) technology to the next generation of New Radio (NR) technology, which may be referred to as the fifth generation (5G). For example, NR is designed to provide lower latency, higher bandwidth or higher throughput, and higher reliability compared to LTE. NR is designed to operate over a wide range of frequency bands, for example, from low frequency bands below about 1 gigahertz (GHz) and intermediate frequency bands from about 1GHz to about 6GHz, to high frequency bands, such as the millimeter wave (mmWave) band. NR is also designed to operate across different spectrum types, from licensed spectrum to unlicensed and shared spectrum. Spectrum sharing enables operators to opportunistically aggregate spectrum to dynamically support high bandwidth services. Spectrum sharing may extend the benefits of NR techniques to operating entities that may not have access to licensed spectrum.

In a wireless communication network, a BS may communicate with a UE in both an uplink direction and a downlink direction. A sidelink is introduced in LTE to allow a UE to send data to another UE without a tunneling BS and/or associated core network. LTE side link technologies have been extended to provide device-to-device (D2D) communication, vehicle networking (V2X) communication, and/or cellular vehicle networking (C-V2X) communication. Similarly, NRs may be extended to support sidelink communications, D2D communications, V2X communications, and/or C-V2X over licensed and/or unlicensed bands.

Brief summary of some examples

The following presents a simplified summary of some aspects of the disclosure in order to provide a basic understanding of the discussed technology. This summary is not an extensive overview of all contemplated features of the disclosure, and is intended to neither identify key or critical elements of all aspects of the disclosure, nor delineate the scope of any or all aspects of the disclosure. Its sole purpose is to present some concepts of one or more aspects of the disclosure in a simplified form as a prelude to the more detailed description that is presented later.

For example, in an aspect of the disclosure, a method of wireless communication performed by a sidelink User Equipment (UE) includes: determining a first starting point from a plurality of starting points; performing Listen Before Talk (LBT) to contend for a Channel Occupancy Time (COT) starting at a first starting point; and transmitting a sidelink communication beginning at a first starting point during the COT based on the LBT.

In an additional aspect of the disclosure, a User Equipment (UE) includes a processor configured to: determining a first starting point from a plurality of starting points; performing Listen Before Talk (LBT) to contend for a Channel Occupancy Time (COT) starting at a first start point; the transceiver is configured to transmit a sidelink communication beginning at a first starting point during the COT based on the LBT.

In an additional aspect of the disclosure, a non-transitory computer-readable medium having program code recorded thereon, the program code comprising: code for causing a sidelink User Equipment (UE) to determine a first starting point from a plurality of starting points; code for causing the sidelink UE to perform Listen Before Talk (LBT) contention for a Channel Occupancy Time (COT) starting at a first start point; and code for causing the sidelink UE to transmit a sidelink communication beginning at a first starting point during the COT based on the LBT.

In an additional aspect of the disclosure, a User Equipment (UE) includes: means for determining a first starting point from a plurality of starting points; means for performing Listen Before Talk (LBT) to contend for a Channel Occupancy Time (COT) starting at a first start point; and means for transmitting a sidelink communication beginning at a first start point during the COT based on the LBT.

Other aspects, features and embodiments of the disclosure will become apparent to those ordinarily skilled in the art upon review of the following description of specific exemplary embodiments of the disclosure in conjunction with the accompanying figures. While features of the disclosure may be discussed below with respect to certain embodiments and figures, all embodiments of the disclosure can include one or more of the advantageous features discussed herein. In other words, while one or more embodiments may have been discussed as having certain advantageous features, one or more of such features may also be used in accordance with the various embodiments of the present disclosure discussed herein. In a similar manner, although example embodiments may be discussed below as device, system, or method embodiments, it should be appreciated that such example embodiments may be implemented in a variety of devices, systems, and methods.

Brief Description of Drawings

Fig. 1 illustrates a wireless communication network in accordance with one or more aspects of the present disclosure.

Fig. 2 is a timing diagram illustrating a transmission frame structure according to one or more aspects of the present disclosure.

Fig. 3 illustrates an example category 4 listen before talk (CAT 4 LBT) scheme in accordance with one or more aspects of the present disclosure.

Fig. 4 is a block diagram of an example User Equipment (UE) in accordance with one or more aspects of the present disclosure.

Fig. 5 is a block diagram of an example Base Station (BS) in accordance with one or more aspects of the present disclosure.

Fig. 6 illustrates a sidelink timeslot structure scheme for sidelink transmission in accordance with one or more aspects of the present disclosure.

Fig. 7 illustrates a sidelink timeslot structure scheme for sidelink transmission in accordance with one or more aspects of the present disclosure.

Fig. 8 illustrates a sidelink timeslot structure scheme for sidelink transmission in accordance with one or more aspects of the present disclosure.

Fig. 9 illustrates a sidelink timeslot structure scheme for sidelink transmission in accordance with one or more aspects of the present disclosure.

Fig. 10 illustrates a flow diagram of a communication method for communicating side-link communications in accordance with one or more aspects of the present disclosure.

Fig. 11 illustrates a flow diagram of a communication method for communicating side-link communications in accordance with one or more aspects of the present disclosure.

Detailed Description

The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details in order to provide a thorough understanding of the various concepts. It will be apparent, however, to one skilled in the art that these concepts may be practiced without these specific details. In some instances, well-known structures and components are shown in block diagram form in order to avoid obscuring such concepts.

The present disclosure relates generally to wireless communication systems (also referred to as wireless communication networks). In various embodiments, the techniques and apparatus may be used for wireless communication networks such as Code Division Multiple Access (CDMA) networks, time Division Multiple Access (TDMA) networks, frequency Division Multiple Access (FDMA) networks, orthogonal FDMA (OFDMA) networks, single carrier FDMA (SC-FDMA) networks, LTE networks, global system for mobile communications (GSM) networks, fifth generation (5G) or New Radio (NR) networks, and other communication networks. As described herein, the terms "network" and "system" may be used interchangeably.

OFDMA networks may implement radio technologies such as evolved UTRA (E-UTRA), institute of Electrical and Electronics Engineers (IEEE) 802.11, IEEE 802.16, IEEE 802.20, flash-OFDM, etc. UTRA, E-UTRA and GSM are part of the Universal Mobile Telecommunications System (UMTS). In particular, long Term Evolution (LTE) is a UMTS release that uses E-UTRA. UTRA, E-UTRA, GSM, UMTS and LTE are described in documents from an organization named "third generation partnership project" (3 GPP), while cdma2000 is described in documents from an organization named "third generation partnership project 2" (3 GPP 2). These various radio technologies and standards are known or under development. For example, the third generation partnership project (3 GPP) is a collaboration between telecommunication association groups that is intended to define a globally applicable third generation (3G) mobile phone specification. The 3GPP Long Term Evolution (LTE) is a 3GPP project aimed at improving the UMTS mobile phone standard. The 3GPP may define specifications for next generation mobile networks, mobile systems, and mobile devices. The present disclosure concerns the evolution of wireless technologies from LTE, 4G, 5G, NR and beyond with shared access to the wireless spectrum between networks using new and different radio access technologies or sets of radio air interfaces.

In particular, 5G networks contemplate diverse deployments, diverse spectrum, and diverse services and devices that may be implemented using a unified OFDM-based air interface. To achieve these goals, in addition to developing new radio technologies for 5G NR networks, further enhancements to LTE and LTE-a are considered. The 5G NR will be able to scale to provide coverage for: (1) With ultra-high density (e.g., about 1M nodes/km) ² ) Ultra-low complexity (e.g., on the order of tens of bits/second), ultra-low energy (e.g., battery life of about 10+ years), and large-scale internet of things (IoT) with deep coverage that can reach challenging locations; (2) Mission critical control including users with strong security (to protect sensitive personal, financial, or confidential information), ultra-high reliability (e.g., about 99.9999% reliability), ultra-low latency (e.g., about 1 millisecond (ms)), and with a wide range of mobility or lack of mobility; and (3) having enhanced mobile broadband, which includes very high capacity (e.g., about 10 Tbps/km) ² ) Extreme data rates (e.g., multiple Gbps rate, 100+ Mbps user experience rate), and deep learning with advanced discovery and optimization.

The 5G NR can be implemented to: using an optimized OFDM-based waveform with scalable parameter design and Transmission Time Interval (TTI); have a common, flexible framework to efficiently multiplex services and features using a dynamic, low latency Time Division Duplex (TDD)/Frequency Division Duplex (FDD) design; and advanced wireless technologies such as massive Multiple Input Multiple Output (MIMO), robust millimeter wave (mmWave) transmission, advanced channel coding, and device-centric mobility. Scalability of the parameter design (and scaling of subcarrier spacing) in 5G NRs can efficiently address operating diverse services across diverse spectrum and diverse deployments. For example, in various outdoor and macro-coverage deployments with less than 3GHz FDD/TDD implementations, the subcarrier spacing may occur at 15 kilohertz (kHz), e.g., over a Bandwidth (BW) of 5, 10, 20 megahertz (MHz). For other various outdoor and small cell coverage deployments of TDD greater than 3GHz, the subcarrier spacing may occur at 30kHz over an 80/100MHz BW. For other various indoor wideband implementations, the subcarrier spacing may occur at 60kHz on a 160MHz BW by using TDD on the unlicensed portion of the 5GHz band. Finally, for various deployments transmitting with 28GHz TDD using mmWave components, subcarrier spacing may occur at 120kHz on a 500MHz BW.

The scalable parameter design of 5G NR facilitates a scalable TTI to meet diverse latency and quality of service (QoS) requirements. For example, shorter TTIs may be used for low latency and high reliability, while longer TTIs may be used for higher spectral efficiency. Efficient multiplexing of long and short TTIs allows transmission to start on symbol boundaries. The 5G NR also contemplates a self-contained integrated subframe design with UL/downlink scheduling information, data, and acknowledgements in the same subframe. Self-contained integrated subframes support communication in unlicensed or contention-based shared spectrum, supporting adaptive UL/downlink that can be flexibly configured on a per-cell basis to dynamically switch between UL and downlink to meet current traffic needs.

Various other aspects and features of the disclosure are described further below. It should be apparent that the teachings herein may be embodied in a wide variety of forms and that any specific structure, function, or both being disclosed herein is merely representative and not limiting. Based on the teachings herein one skilled in the art should appreciate that an aspect disclosed herein may be implemented independently of any other aspects and that two or more of these aspects may be combined in various ways. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. In addition, such an apparatus may be implemented or such a method may be practiced using other structure, functionality, or structure and functionality in addition to or other than one or more of the aspects set forth herein. For example, the methods may be implemented as part of a system, apparatus, device, and/or as instructions stored on a computer-readable medium for execution on a processor or computer. Furthermore, an aspect may comprise at least one element of a claim.

NR techniques have been extended to operate over unlicensed spectrum. The deployment of NR technology on unlicensed spectrum is referred to as NR-U. The goal of NR-U is to operate on the 5 gigahertz (GHz) and 6GHz frequency bands, where there are well-defined channel access rules for sharing among operators of the same Radio Access Technology (RAT) and/or different RATs. When a BS operates on an unlicensed spectrum, the BS does not have ownership or control of the spectrum. Thus, the BS contends for channel access in the spectrum, e.g., via a Clear Channel Assessment (CCA) and/or a Listen Before Talk (LBT) procedure.

Provisioning sidelink services, such as device-to-device (D2D), vehicle-to-vehicle (V2V), vehicle-to-vehicle (V2X), and/or cellular vehicle-to-vehicle (C-V2X) communications, on a dedicated or licensed spectrum is relatively straightforward because channel access in the dedicated or licensed spectrum is guaranteed. NR-U may benefit sidelink services, for example, by inexpensively offloading sidelink traffic to the unlicensed spectrum. However, channel access in a shared spectrum or an unlicensed spectrum is not guaranteed. Thus, to provision sidelink services over a shared spectrum or an unlicensed spectrum, sidelink user equipment devices (UEs) contend for channel access in the spectrum, e.g., via CCA and/or LBT procedures.

A side link UE may receive or transmit V2X side link communications using a multiple side link slot structure configuration. The plurality of sidelink slot structure configurations may include a first sidelink slot structure configuration for Physical Sidelink Control Channel (PSCCH)/physical sidelink shared channel (PSCCH) transmissions and a second sidelink slot structure configuration for Physical Sidelink Feedback Channel (PSFCH) communications (e.g., receiving a PSFCH or transmitting a PSFCH). The first side link slot structure configuration may include fourteen symbols (e.g., OFDM symbols) in a slot, with a total of thirteen symbols for the PSCCH/PSCCH, and the last symbol in the slot left as a transmission gap (in the case of no transmission). A first symbol of the thirteen symbols may be a repetition of a second symbol in the slot, where the first symbol is located at the beginning of the slot and immediately before the second symbol. The first symbol immediately precedes the second symbol if the second symbol follows the first symbol and there are no other symbols between the first symbol and the second symbol. Additionally, the first sidelink slot structure configuration may be devoid of a PSFCH. In other words, the starting symbol of the slot may be followed by twelve consecutive symbols for PSCCH/PSCCH, followed by a gap duration in the last symbol of the slot. In the first side link slot structure configuration, the first symbol is used for Automatic Gain Control (AGC) and the last symbol is used for gap. The AGC detects the signal energy in the channel and applies hardware gain to maximize the signal amplitude to the dynamic range (for ADC) at the receiver. The receiver determines a gain of the received signal, and the AGC is for a time that allows for the receiver to determine the gain and apply the gain (e.g., a hardware gain component) such that the gain has been adjusted when the receiver receives data (e.g., in a next symbol).

The second sidelink slot structure configuration may include fourteen symbols (e.g., OFDM symbols) in a slot, with a total of ten symbols for PSCCH/PSCCH transmissions. In a second sidelink slot structure configuration, a first symbol of the slot may be a repetition of a second symbol in the slot, where the first symbol is located at the beginning of the slot and immediately before the second symbol. The first symbol is followed by nine consecutive symbols for the PSCCH/PSCCH, followed by a first gap duration. The first gap duration is followed by a second repeating symbol that is a repetition of the PSFCH symbol, wherein the second repeating symbol immediately precedes the PSFCH symbol. The second slot duration is after the PSFCH symbol and is the last symbol of the slot.

The side-link UE may initiate LBT itself to acquire the COT without being controlled by a centralized structure (e.g., the BS 105 in the network 100). Accordingly, multiple initiator sidelink UEs may contend for the medium at or about the same time to acquire the COT. For example, multiple UEs may each start performing LBT at the same slot or mini-slot boundary. Accordingly, the system may become congested with multiple initiator sidelink UEs, where each initiator sidelink UE may experience a large number of LBT failures. Additionally or alternatively, the transmission starting points of multiple UEs may be aligned to the same slot boundary or mini-slot boundary. If multiple initiator side link UEs transmit data at or around the same time, interference between UEs may occur. Additionally, a similar problem may arise if multiple UEs activate CG-UL at the same time to acquire COT in the CG-UL scenario. It may be desirable to provide congestion control mechanisms for sidelink communications.

The present application describes mechanisms for providing multiple starting points for Channel Occupancy Time (COT) for sidelink communication in a frequency band among sidelink UEs. The multiple starting points may mitigate congestion by allowing multiple UEs to perform LBT and/or initiate transmission of sidelink communications at different times relative to each other.

In some aspects, an initiator sidelink UE may define a plurality of starting points for transmitting sidelink communications and determine a first starting point from the plurality of starting points. The UE may perform CAT4LBT to contend for COT and initiate transmission of sidelink communications starting at the selected starting point if the CAT4LBT results in LBT passing. After acquiring the COT, the UE may transmit sidelink data to the other side link UE via a Physical Sidelink Shared Channel (PSSCH), a Physical Sidelink Control Channel (PSCCH), and/or a Physical Sidelink Feedback Channel (PSFCH). The UE acquiring the COT may be referred to as an initiator UE, and may transmit Sidelink Control Information (SCI) indicating COT sharing information. The UE monitoring the SCI may be referred to as a monitoring UE. Further, a UE that does not acquire a COT but shares a COT acquired by another UE may be referred to as a responder UE.

A particular frequency band may have particular channel occupancy requirements. The channel occupancy may be defined by the continuous transmission in the channel. In slot-based transmission, the initiating UE may continue to communicate and share the COT during the COT as long as the initiating UE continues to occupy the channel. Due to the channel occupancy requirement, the UE may agree to relinquish the channel if the UE does not occupy the channel for the LBT gap time threshold. In some examples, depending on the selected starting point, a first duration between the selected starting point and the next symbol of the COT may allow another UE to intervene and transmit during the first duration. To avoid this problem, the UE may fill the first duration by transmitting a CP extension during the first duration. For example, the UE may apply the CP extension to sidelink transmissions and transmit sidelink communications with the CP extension. In some examples, if the selected starting point is within a symbol that includes an Automatic Gain Control (AGC) symbol, the UE may puncture a portion of the symbol and transmit a sidelink communication that begins at the starting point of the COT. The mechanism for selecting a starting point from a plurality of starting points and transmitting a sidelink communication starting at that starting point of the COT is described in more detail herein.

Aspects of the present disclosure may provide several benefits. For example, allowing a UE to select a starting point from a plurality of starting points for transmitting sidelink communications may reduce congestion for UEs initiating a COT. Accordingly, the UE may have a higher likelihood of transmitting a sidelink communication that begins at the selected starting point. In another example, applying CP extensions with CP extension lengths to sidelink transmissions of an originating UE may allow the UE to transmit sidelink communications without interfering with another UE. Thus, the disclosed examples may consume less time and less resources.

Fig. 1 illustrates a wireless communication network 100 in accordance with one or more aspects of the present disclosure. The network 100 may be a 5G network. The network 100 includes a number of Base Stations (BSs) 105 (labeled 105a, 105b, 105c, 105d, 105e, and 105f, respectively) and other network entities. The BS 105 may be a station that communicates with the UEs 115 and may also be referred to as an evolved node B (eNB), a next generation eNB (gNB), an access point, and so on. Each BS 105 may provide communication coverage for a particular geographic area. In 3GPP, the term "cell" can refer to the particular geographic coverage area of the BS 105 and/or the BS subsystem serving that coverage area, depending on the context in which the term is used.

The BS 105 may provide communication coverage for macro cells or small cells (such as pico cells or femto cells), and/or other types of cells. A macro cell generally covers a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs with service subscriptions with the network provider. Small cells (such as picocells) typically cover a relatively small geographic area and may allow unrestricted access by UEs with service subscriptions with the network provider. Small cells, such as femtocells, typically also cover a relatively small geographic area (e.g., a home), and may have restricted access by UEs associated with the femtocell (e.g., UEs in a Closed Subscriber Group (CSG), UEs of users in the home, etc.) in addition to unrestricted access. The BS for the macro cell may be referred to as a macro BS. The BS for the small cell may be referred to as a small cell BS, a pico BS, a femto BS, or a home BS. In the example shown in fig. 1, BSs 105D and 105e may be conventional macro BSs, while BSs 105a-105c may be one of three-dimensional (3D), full-dimensional (FD), or massive MIMO enabled macro BSs. The BSs 105a-105c may leverage their higher dimensional MIMO capabilities to increase coverage and capacity with 3D beamforming in both elevation and azimuth beamforming. The BS 105f may be a small cell BS, which may be a home node or a portable access point. The BS 105 may support one or more (e.g., two, three, four, etc.) cells.

The network 100 may support synchronous or asynchronous operation. For synchronous operation, the BSs may have similar frame timing, and transmissions from different BSs may be approximately aligned in time. For asynchronous operation, BSs may have different frame timing, and transmissions from different BSs may not be aligned in time.

UEs 115 are dispersed throughout wireless network 100, and each UE 115 may be stationary or mobile. UE 115 may also be referred to as a terminal, mobile station, subscriber unit, station, etc. The UE 115 may be a cellular telephone, a Personal Digital Assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a tablet computer, a laptop computer, a cordless telephone, a Wireless Local Loop (WLL) station, and so forth. In one aspect, the UE 115 may be a device that includes a Universal Integrated Circuit Card (UICC). In another aspect, the UE may be a device that does not include a UICC. In some aspects, a UE 115 that does not include a UICC may also be referred to as an IoT device or an internet of everything (IoE) device. The UEs 115a-115d are examples of mobile smartphone type devices that access the network 100. The UE 115 may also be a machine specifically configured for connected communications including Machine Type Communications (MTC), enhanced MTC (eMTC), narrowband IoT (NB-IoT), etc. UEs 115e-115h are examples of various machines of access network 100 that are configured for communication. The UEs 115i-115k are examples of vehicles equipped with wireless communication devices of the access network 100 that are configured for communication. The UE 115 may be capable of communicating with any type of BS (whether a macro BS, a small cell, etc.). In fig. 1, a lightning bundle (e.g., a communication link) indicates a wireless transmission between a UE 115 and a serving BS 105, a desired transmission between BSs 105, a backhaul transmission between BSs, or a sidelink transmission between UEs 115, the serving BS 105 being a BS designated to serve the UE 115 on a Downlink (DL) and/or an Uplink (UL).

In operation, the BSs 105a-105c may serve the UEs 115a and 115b using 3D beamforming and coordinated spatial techniques, such as coordinated multipoint (CoMP) or multi-connectivity. The macro BS 105d may perform backhaul communications with the BSs 105a-105c, as well as the small cell BS 105 f. The macro BS 105d may also transmit multicast services subscribed to and received by the UEs 115c and 115 d. Such multicast services may include mobile television or streaming video, or may include other services for providing community information (such as weather emergencies or alerts, such as amber alerts or grey alerts).

The BS 105 may also communicate with a core network. The core network may provide user authentication, access authorization, tracking, internet Protocol (IP) connectivity, and other access, routing, or mobility functions. At least some BSs 105 (e.g., which may be examples of a gNB or Access Node Controller (ANC)) may interface with a core network over a backhaul link (e.g., NG-C, NG-U, etc.) and may perform radio configuration and scheduling for communication with UEs 115. In various examples, the BSs 105 can communicate with each other directly or indirectly (e.g., through a core network) over backhaul links (e.g., X1, X2, etc.), which can be wired or wireless communication links.

The network 100 may also support mission-critical communications with ultra-reliable and redundant links for mission-critical devices, such as UE 115e, which may be drones. The redundant communication links with the UE 115e may include links from the macro BSs 105d and 105e, and links from the small cell BS 105 f. Other machine type devices, such as UE 115f (e.g., a thermometer), UE 115g (e.g., a smart meter), and UE 115h (e.g., a wearable device), may communicate with BSs, such as small cell BS 105f and macro BS 105e, directly through network 100, or in a multi-step configuration by communicating with another user device that relays its information to the network (such as UE 115f communicating temperature measurement information to smart meter UE 115g, which is then reported to the network through small cell BS 105 f). The network 100 may also provide additional network efficiency through dynamic, low latency TDD/FDD communications, such as V2V, V2X, C-V2X communications between the UE 115I, 115j, or 115k and other UEs 115, and/or vehicle-to-infrastructure (V2I) communications between the UE 115I, 115j, or 115k and the BS 105.

In some implementations, the network 100 utilizes OFDM-based waveforms for communication. An OFDM-based system may divide the system BW into multiple (K) orthogonal subcarriers, which are also commonly referred to as subcarriers, tones, bins, and so on. Each subcarrier may be modulated with data. In some examples, the subcarrier spacing between adjacent subcarriers may be fixed, and the total number of subcarriers (K) may be dependent on the system BW. The system BW may also be divided into sub-bands. In other examples, the subcarrier spacing and/or the duration of the TTI may be scalable.

In some aspects, the BS 105 may assign or schedule transmission resources (e.g., in the form of time-frequency Resource Blocks (RBs)) for Downlink (DL) and Uplink (UL) transmissions in the network 100. DL refers to a transmission direction from the BS 105 to the UE 115, and UL refers to a transmission direction from the UE 115 to the BS 105. The communication may take the form of radio frames. A radio frame may be divided into a number of subframes or slots, e.g. about 10. Each time slot may be further divided into sub-slots. In FDD mode, simultaneous UL and DL transmissions may occur in different frequency bands. For example, each subframe includes a UL subframe in a UL frequency band and a DL subframe in a DL frequency band. In TDD mode, UL and DL transmissions occur at different time periods using the same frequency band. For example, a subset of subframes in a radio frame (e.g., DL subframes) may be used for DL transmissions and another subset of subframes in a radio frame (e.g., UL subframes) may be used for UL transmissions.

The DL subframe and the UL subframe may be further divided into several regions. For example, each DL or UL subframe may have a predefined area for transmission of reference signals, control information, and data. The reference signal is a predetermined signal that facilitates communication between the BS 105 and the UE 115. For example, a reference signal may have a particular pilot pattern or structure in which pilot tones may span an operating BW or band, each pilot tone being located at a predefined time and a predefined frequency. For example, the BS 105 may transmit cell-specific reference signals (CRS) and/or channel state information-reference signals (CSI-RS) to enable the UEs 115 to estimate the DL channel. Similarly, the UE 115 may transmit a Sounding Reference Signal (SRS) to enable the BS 105 to estimate the UL channel. The control information may include resource assignments and protocol controls. The data may include protocol data and/or operational data. In some aspects, the BS 105 and the UE 115 may communicate using self-contained subframes. The self-contained subframe may include a portion for DL communication and a portion for UL communication. The self-contained subframes may be DL-centric or UL-centric. The DL centric sub-frame may comprise a longer duration for DL communication than for UL communication. The UL centric sub-frame may comprise a longer duration for UL communications than for DL communications.

In some aspects, the network 100 may be an NR network deployed over a licensed spectrum. The BS 105 may transmit synchronization signals (e.g., including a Primary Synchronization Signal (PSS) and a Secondary Synchronization Signal (SSS)) in the network 100 to facilitate synchronization. BS 105 may broadcast system information associated with network 100 (e.g., including a Master Information Block (MIB), remaining system information (RMSI), and Other System Information (OSI)) to facilitate initial network access. In some examples, BS 105 may broadcast PSS, SSS, and/or MIB in the form of Synchronization Signal Blocks (SSBs) on a Physical Broadcast Channel (PBCH), and may broadcast RMSI and/or OSI on a Physical Downlink Shared Channel (PDSCH).

In some aspects, a UE 115 attempting to access the network 100 may perform an initial cell search by detecting a PSS from the BS 105. The PSS may enable synchronization of the period timing and may indicate a physical layer identity value. The UE 115 may then receive the SSS. The SSS may enable radio frame synchronization and may provide a cell identity value that may be combined with a physical layer identity value to identify the cell. The PSS and SSS may be located in the center portion of the carrier or at any suitable frequency within the carrier.

After receiving the PSS and SSS, UE 115 may receive the MIB. The MIB may include system information for initial network access and scheduling information for RMSI and/or OSI. After decoding the MIB, UE 115 may receive RMSI and/or OSI. The RMSI and/or OSI may include Radio Resource Control (RRC) information related to Random Access Channel (RACH) procedures, paging, control resource sets (CORESET) for Physical Downlink Control Channel (PDCCH) monitoring, physical UL Control Channel (PUCCH), physical UL Shared Channel (PUSCH), power control, and SRS.

After obtaining MIB, RMSI, and/or OSI, UE 115 may perform a random access procedure to establish a connection with BS 105. In some examples, the random access procedure may be a four-step random access procedure. For example, the UE 115 may transmit a random access preamble and the BS 105 may respond with a random access response. The Random Access Response (RAR) may include a detected random access preamble Identifier (ID), timing Advance (TA) information, UL grant, temporary cell radio network temporary identifier (C-RNTI), and/or backoff indicator corresponding to the random access preamble. Upon receiving the random access response, the UE 115 may transmit a connection request to the BS 105 and the BS 105 may respond with the connection response. The connection response may indicate a contention resolution scheme. In some examples, the random access preamble, RAR, connection request, and connection response may be referred to as message 1 (MSG 1), message 2 (MSG 2), message 3 (MSG 3), and message 4 (MSG 4), respectively. In some examples, the random access procedure may be a two-step random access procedure in which the UE 115 may transmit a random access preamble and a connection request in a single transmission, and the BS 105 may respond by transmitting a random access response and a connection response in a single transmission.

After establishing the connection, the UE 115 and the BS 105 can enter a normal operation phase, in which operational data can be exchanged. For example, the BS 105 may schedule the UE 115 for UL and/or DL communications. The BS 105 may transmit UL and/or DL scheduling grants to the UE 115 via the PDCCH. The scheduling grant may be transmitted in the form of DL Control Information (DCI). The BS 105 may transmit DL communication signals (e.g., carrying data) to the UE 115 via the PDSCH in accordance with the DL scheduling grant. The UE 115 may transmit UL communication signals to the BS 105 via PUSCH and/or PUCCH according to the UL scheduling grant.

In some aspects, the BS 105 may communicate with the UE 115 using HARQ techniques to improve communication reliability, e.g., to provide URLLC service. The BS 105 may schedule the UE 115 for PDSCH communication by transmitting a DL grant in the PDCCH. The BS 105 may transmit DL data packets to the UE 115 according to scheduling in the PDSCH. The DL data packets may be transmitted in the form of Transport Blocks (TBs). If the UE 115 successfully receives the DL data packet, the UE 115 may transmit a HARQ ACK to the BS 105. Conversely, if the UE 115 fails to successfully receive the DL transmission, the UE 115 may transmit a HARQ NACK to the BS 105. Upon receiving the HARQ NACK from the UE 115, the BS 105 retransmits the DL data packet to the UE 115. The retransmission may include the same encoded version of the DL data as the initial transmission. Alternatively, the retransmission may include a different encoded version of the DL data than the initial transmission. The UE 115 may apply soft combining to combine the encoded data received from the initial transmission and retransmission for decoding. The BS 105 and the UE 115 may also apply HARQ to UL communications using a mechanism substantially similar to DL HARQ.

In some aspects, the network 100 may operate on a system BW or a Component Carrier (CC) BW. Network 100 may divide system BW into multiple BWPs (e.g., multiple portions). The BS 105 may dynamically assign the UE 115 to operate on a certain BWP (e.g., a certain portion of the system BW). The assigned BWP may be referred to as an active BWP. The UE 115 may monitor the active BWP for signaling information from the BS 105. The BS 105 may schedule the UE 115 for UL or DL communication in active BWP. In some aspects, the BS 105 may assign BWP pairs within a CC to the UEs 115 for UL and DL communications. For example, the BWP pair may include one BWP for UL communications and one BWP for DL communications.

In some aspects, the network 100 may operate on a shared channel, which may include a shared frequency band or an unlicensed frequency band. For example, the network 100 may be an NR unlicensed (NR-U) network operating on an unlicensed band. In such aspects, the BS 105 and the UE 115 may be operated by multiple network operating entities. To avoid collisions, the BS 105 and the UE 115 may employ LBT procedures to monitor transmission opportunities (TXOPs) in a shared channel. A wireless communication device may perform LBT in a shared channel. LBT is a channel access scheme that may be used in unlicensed spectrum. When the LBT result is that the LBT passed (the wireless communication device wins contention for the wireless medium), the wireless communication device may access the shared medium to transmit and/or receive data. For example, a transmitting node (e.g., BS 105 or UE 115) may perform LBT before transmitting in a channel. When the LBT passes, the transmitting node may proceed to transmit. When LBT fails, the transmitting node may refrain from transmitting in the channel. In an example, LBT may be based on energy detection. For example, the LBT result is a pass when the measured signal energy from the channel is below a threshold. Conversely, when the measured signal energy from the channel exceeds a threshold, the LBT result is a failure. In another example, LBT may be based on signal detection. For example, when a channel reservation signal (e.g., a predetermined preamble signal) is not detected in the channel, the LBT result is pass. In contrast, when a channel reservation signal is detected in the channel, the LBT result is a failure. The TXOP may also be referred to as a Channel Occupancy Time (COT).

Sidelink communication refers to communication among UEs that does not require a tunneling BS and/or core network. For example, sidelink communication may refer to communication between two devices that does not pass through a BS. The side link communications may be communicated over a physical side link control channel (PSCCH) and a physical side link shared channel (pscsch). PSCCH and PSCCH are similar to a Physical Downlink Control Channel (PDCCH) and a Physical Downlink Shared Channel (PDSCH) in Downlink (DL) communication between a BS and a UE. For example, the PSCCH may carry side link control information (SCI) and the PSCCH may carry SCI and/or side link data (e.g., user data). Each PSCCH is associated with a corresponding PSCCH, where the SCIs in the PSCCH may carry reservation and/or scheduling information for side link data transmissions in the associated PSCCH. In some examples, the UE may transmit a PSSCH carrying the SCI, which may be indicated in two stages. In first phase control (SCI-1), the UE may transmit a PSCCH carrying information for resource allocation and decoding second phase control. The first stage SCI may include at least one of: priority, psch resource assignment, resource reservation period (if enabled), psch DMRS pattern (if more than one pattern is configured), second stage SCI format (e.g., size of second SCI), amount of resources used for second stage SCI, number of psch demodulation reference signal (DMRS) ports(s), modulation and Coding Scheme (MCS), and so on. In second stage control (SCI-2), the UE may transmit a PSCCH carrying information for decoding the PSCCH. The second stage SCI may include a 1-bit L1 destination Identifier (ID), an 8-bit L1 resource ID, an HARQ process ID, a New Data Indicator (NDI), and a Redundancy Version (RV), etc. Sidelink communications may also be communicated over a physical sidelink feedback control channel (PSFCH), which indicates an Acknowledgement (ACK) -Negative Acknowledgement (NACK) to a previously transmitted PSSCH. Use cases for side link communication may include vehicle networking (V2X), industrial IoT (IIot), and/or NR-light.

Some UEs 115 may communicate with each other in peer-to-peer communication. For example, a first UE may communicate with a second UE on a sidelink. In some instances, the sidelinks may be unicast bi-directional links, each sidelink between a pair of UEs. In some other examples, the sidelink may be a multicast link that supports multicast sidelink services among UEs. For example, a first UE may transmit multicast data to a second UE on a sidelink. In some aspects, some UEs are associated with a vehicle (e.g., similar to UEs 115i-k in fig. 1), and the communication on the sidelink may be C-V2X communication. C-V2X communication may refer to communication between a vehicle and any other wireless communication device in a cellular network.

NR supports two Radio Resource Allocation (RRA) modes, mode 1RRA and mode 2RRA, for the side link on the licensed spectrum. Mode 1RRA supports network controlled RRA that can be used to cover inner link communications. For example, the serving BS may determine radio resources on behalf of the sidelink UE and transmit an indication of the radio resources to the sidelink UE. The serving BS may provide dynamic grants or may activate configured sidelink grants for sidelink communications. The side link feedback may be reported back to the BS by the transmitting UE. Mode 2RRA supports autonomous RRA for sidelink UEs to perform autonomous sidelink communications over a shared radio frequency band (e.g., in a shared radio spectrum or an unlicensed spectrum). In some aspects, a shared radio frequency band may be divided into multiple subchannels or frequency sub-bands. The side-link UE may be configured to operate in mode 2RRA. For example, a side-link UE may be configured with a pool of resources in a shared radio band. Additionally, channel access may be in units of sidelink communication frames in time. Each sidelink communication frame may include an LBT gap duration followed by sidelink resources. A sidelink UE intended for transmission in a frequency sub-band may perform LBT in an LBT gap duration. If the LBT is successful, the sidelink UE may proceed to transmit SCI and/or sidelink data in subsequent sidelink resources.

Multiple UEs may perform LBT in contention for COT. Instead of the UE 115 performing LBT to contend for COT and/or transmitting the sidelink communications at the same slot or mini-slot boundary as other UEs, the UE 115 may select a starting point from a plurality of starting points and transmit the sidelink communications beginning at the selected starting point. Each UE of the plurality of UEs may select a different starting point from a plurality of starting points. Accordingly, congestion for each sidelink UE initiating the COT or transmission interference between UEs may be reduced.

LBT may be in various modes. The LBT mode may be, for example, class 4 (CAT 4) LBT, class 2 (CAT 2) LBT, or class 1 (CAT 1) LBT. CAT1 LBT is referred to as LBT-free mode, where LBT is not performed before transmission. CAT2LBT refers to LBT without a random backoff period. For example, the transmitting node may determine a channel measurement within a time interval and determine whether the channel is available based on a comparison of the channel measurement to an ED threshold. CAT4LBT refers to LBT with random backoff and variable Contention Window (CW). The initiator UE may perform CAT4LBT to acquire the COT. CAT4LBT is generally more complex than CAT2LBT because, for example, the timing for CAT4LBT is not as fixed as the timing for CAT2 LBT.

Techniques are provided for determining a starting point of a plurality of starting points at which a UE may initiate transmission of a sidelink communication. Mechanisms for communicating sidelink communications beginning at the determined starting point are described in more detail herein.

Fig. 2 is a timing diagram illustrating a transmission frame structure 200 according to one or more aspects of the present disclosure. The transmission frame structure 200 may be employed by a BS (such as BS 105) and a UE (such as UE 115) in a network (such as network 100) for communication. The BS may communicate with the UE using configured time-frequency resources as shown in the transmission frame structure 200. Additionally or alternatively, the side link UE may autonomously select side link resources or identify side link resources for side link communication with network assistance from the BS. For example, a first side-link UE may communicate with another side-link UE using configured time-frequency resources as shown in the transmission frame structure 200. In fig. 2, the x-axis represents time in some arbitrary units, while the y-axis represents frequency in some arbitrary units.

The transmission frame structure 200 includes a radio frame 201. The duration of the radio frame 201 may vary depending on some aspects. In an example, the radio frame 201 may have a duration of about 10 milliseconds. Radio frame 201 includes a number M of time slots 202, where M may be any suitable positive integer. In one example, M may be about 10.

Each slot 202 includes a number of subcarriers 204 in frequency and a number of symbols 206 in time. The number of subcarriers 204 and/or the number of symbols 206 in a slot 202 may vary depending on, for example, channel bandwidth, subcarrier spacing (SCS), and/or Cyclic Prefix (CP) pattern. One subcarrier 204 in the form of frequency and one symbol 206 in the form of time form one Resource Element (RE) 212 for transmission. A Resource Block (RB) 210 is formed from a number of consecutive subcarriers 204 in frequency and a number of consecutive symbols 206 in time. A Resource Block Group (RBG) may include one or more RBs. A sub-band may include multiple RBGs.

In an example, a sidelink UE (e.g., UE 115 in fig. 1) may schedule sidelink transmissions for UL and/or DL communications at a time granularity of a timeslot 202 or a mini-timeslot 208. Each time slot 202 may be time divided into a number P of mini-slots 208. Each mini-slot 208 may include one or more symbols 206. The mini-slots 208 in the time slots 202 may have variable lengths. For example, when the slot 202 includes a number N of symbols 206, the mini-slot 208 may have a length between 1 symbol 206 and (N-1) symbols 206. In some aspects, the mini-slot 208 may have a length of about two symbols 206, about four symbols 206, or about seven symbols 206. In some examples, the BS 105 may schedule the UEs 115 at a frequency granularity of an RB 210 (e.g., including about 12 subcarriers 204).

Fig. 3 illustrates an example CAT4LBT aspect 300 in accordance with one or more aspects of the present disclosure. The CAT4LBT scheme 300 may be employed by UEs 115 in a network, such as network 100. The x-axis represents time in some arbitrary units.

In the example illustrated in fig. 3, the frequency band 302 may be a shared radio band or an unlicensed frequency band that is shared by multiple network operating entities. Band 302 may, for example, have a BW of about 10MHz or about 20 MHz. In one example, the SCS is about kHz, and the overall symbol length can be about 66.68 μ s. In one example, the SCS is about 30kHz, while the overall symbol length can be about 33.34 μ s. In one example, the SCS is approximately 60kHz, while the overall symbol length can be approximately 16.67 μ s. Band 302 may be located at any suitable frequency. In some aspects, frequency band 302 may be located at approximately 3.5GHz, 6GHz, or 20 GHz.

A UE 115 may contend for a COT 304 in a frequency band 302 for sidelink communication with another UE on a sidelink, which frequency band 302 may be a shared radio band and/or an unlicensed band. To communicate sidelink communications over frequency band 302, UE 115 may perform LBT to contend for COT 304 in frequency band 302. As discussed, LBT may refer to a channel sensing mechanism used by a device (e.g., UE 115) to determine the presence of other signals in a channel prior to transmission and avoid collisions with other transmissions. The device may listen to the medium for a period of time. CAT4LBT may refer to LBT with random backoff and variable CW.

In an example, the UE 115 may perform CAT4LBT 306 to contend for COT 304. If CAT4LBT 306 results in an LBT failure, the UE 115 may determine that the band 302 is occupied and may refrain from transmitting in the band 302 accordingly. For example, the CAT4LBT 306 may include a deferral period 312, the deferral period 312 including a deferral duration 314 and n time delays (Td) 316, where n is an integer greater than zero. The n parameter may be related to a Channel Access Priority Class (CAPC), and each Td 316 may be 9 μ s or about 9 μ s. In the example illustrated in fig. 3, the deferral duration 314 may be 16 μ s or approximately 16 μ s, and n may be 3. Accordingly, the deferral period 312 may be approximately 43 μ β.

CAT4LBT 306 may also include a variable CW 310, which variable CW 310 may be calculated according to N time delays (Td) 316, where N is an integer greater than zero and is randomly and uniformly distributed between 0 and CW size. CW may refer to a mechanism that allows UE 115 to back off when there is potential congestion in frequency band 302. The size of the variable CW 310 may be doubled (up to a maximum size) if the UE 115 senses congestion in the frequency band 302. The size of the variable CW 310 may be reset to a minimum size if the UE 115 senses no congestion in the frequency band 302. The resizing may be driven by decoding errors (e.g., decoding errors may be used as an approximation of collision events). In the example illustrated in fig. 3, N may be 5, and variable CW 310 may therefore be approximately 45 μ β.

If CAT4LBT 306 is successful, the UE 115 may proceed to use COT 304 for sidelink communications 320. In this example, UE 115 may communicate sidelink communications 320 with another UE in frequency band 302 during COT 304. For example, UE 115 may acquire COT 304 and transmit sidelink communications 320 that include PSCCH, and/or PSFCH.

The side-link UE may initiate LBT itself to acquire the COT without being controlled by a centralized architecture (e.g., the BS 105 in the network 100). Accordingly, multiple initiator sidelink UEs may contend for the medium at or around the same time to acquire the COT. For example, multiple UEs may each start performing LBT at the same slot boundary. Accordingly, the system may become congested with multiple initiator sidelink UEs, where each initiator sidelink UE may experience a large number of LBT failures. Additionally or alternatively, the transmission starting points of multiple UEs may be aligned to the same slot boundary or mini-slot boundary. If multiple initiator side link UEs transmit data at or around the same time, interference between UEs may occur.

Additionally, a similar problem may arise if multiple UEs activate CG-UL at the same time to acquire COT in the CG-UL scenario. It may be desirable to provide congestion control mechanisms for sidelink communications. In some aspects, the initiator sidelink UE 115 may define a plurality of starting points for transmitting sidelink communications and determine a first starting point from the plurality of starting points. The UE 115 may randomly select a starting point among the configured starting points, e.g., based on a uniform distribution function. The UE may perform CAT4LBT to contend for COT and initiate transmission of sidelink communications starting at the selected starting point if the CAT4LBT results in LBT passing. Depending on the selected starting point, a first duration between the selected starting point and the next symbol of the COT may allow another UE to intervene and transmit during the first duration. To avoid this problem, the UE 115 may fill the first duration by transmitting the CP extension during the first duration. Mechanisms are provided in the present disclosure for selecting a starting point from a plurality of starting points and transmitting sidelink communications beginning at the starting point.

Fig. 4 is a block diagram of an example UE 400 in accordance with one or more aspects of the present disclosure. UE 400 may be UE 115 as discussed in fig. 1 above. As shown, UE 400 may include a processor 402, a memory 404, a COT module 408, a sidelink communications module 409, a transceiver 410 including a modem subsystem 412 and a Radio Frequency (RF) unit 414, and one or more antennas 416. These elements may communicate with each other, directly or indirectly, for example, via one or more buses.

The processor 402 may include a Central Processing Unit (CPU), a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a controller, a Field Programmable Gate Array (FPGA) device, another hardware device, a firmware device, or any combination thereof, configured to perform the operations described herein. The processor 402 may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

The memory 404 may include cache memory (e.g., cache memory of the processor 402), random Access Memory (RAM), magnetoresistive RAM (MRAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), flash memory, solid-state memory devices, hard drives, other forms of volatile and non-volatile memory, or combinations of different types of memory. In an aspect, memory 404 includes non-transitory computer-readable media. The memory 404 may store or have instructions 406 recorded thereon. The instructions 406 may include instructions that, when executed by the processor 402, cause the processor 402 to perform the operations described herein with reference to the UE 115 in connection with aspects of the disclosure (e.g., aspects of fig. 1-3 and 6-11). The instructions 406 may also be referred to as program code. The program code may be for causing a wireless communication device to perform the operations, for example, by causing one or more processors, such as processor 402, to control or instruct the wireless communication device to do so. The terms "instructions" and "code" should be construed broadly to include any type of computer-readable statements. For example, the terms "instructions" and "code" may refer to one or more programs, routines, subroutines, functions, procedures, and the like. The "instructions" and "code" may comprise a single computer-readable statement or a plurality of computer-readable statements.

COT module 408 and/or sidelink communication module 409 may be implemented via hardware, software, or a combination thereof. For example, the COT module 408 and/or the sidelink communication module 409 may be implemented as a processor, circuitry, and/or instructions 406 stored in the memory 404 and executed by the processor 402. In some examples, COT module 408 and/or sidelink communication module 409 may be integrated within modem subsystem 412. For example, the COT module 408 and/or the sidelink communication module 409 may be implemented by a combination of software components (e.g., executed by a DSP or general purpose processor) and hardware components (e.g., logic gates and circuitry) within the modem subsystem 412.

The COT module 408 and/or the sideline communication module 409 may be used in various aspects of the disclosure, such as the aspects of fig. 1-3 and 6-11. In some aspects, the COT module 408 may be configured to determine a first starting point from a plurality of starting points. The COT module 408 may be configured to perform LBT to contend for a COT starting at a first start point. The sidelink communication module 408 may be configured to transmit sidelink communications beginning at a first start point during the COT based on the LBT.

As shown, transceiver 410 may include a modem subsystem 412 and an RF unit 414. The transceiver 410 may be configured to communicate bi-directionally with other devices, such as the BS 105. Modem subsystem 412 may be configured to modulate and/or encode data from memory 404, COT module 408, and/or sidelink communication module 409 according to an MCS (e.g., a Low Density Parity Check (LDPC) coding scheme, a turbo coding scheme, a convolutional coding scheme, a digital beamforming scheme, etc.). RF unit 414 may be configured to process (e.g., perform analog-to-digital conversion, digital-to-analog conversion, etc.) modulated/encoded data (e.g., PSCCH data and/or PSCCH control information, PSFCH ACK/NACK feedback, sidelink communications) from modem subsystem 412 (on an out-of-band transmission) or a transmission originating from another source, such as UE 115 or BS 105. The RF unit 414 may be further configured to perform analog beamforming in conjunction with digital beamforming. Although shown as being integrated together in the transceiver 410, the modem subsystem 412 and the RF unit 414 may be separate devices that are coupled together at the UE 115 to enable the UE 115 to communicate with other devices.

RF unit 414 may provide modulated and/or processed data, such as data packets (or more generally data messages that may contain one or more data packets and other information), to antenna 416 for transmission to one or more other devices. The antenna 416 may further receive data messages transmitted from other devices. The antenna 416 may provide the received data message for processing and/or demodulation at the transceiver 410. The transceiver 410 may provide the demodulated and/or decoded data (e.g., PSCCH data and/or PSCCH control information, PSCCH ACK/NACK feedback, sidelink communications) to the COT module 408 and/or the sidelink communications module 409 for processing. The antenna 416 may include multiple antennas of similar or different designs in order to maintain multiple transmission links. The RF unit 414 may be configured with an antenna 416.

In some examples, transceiver 410 is configured to transmit sidelink communications beginning at a first starting point during the COT based on the LBT, e.g., by coordinating with sidelink communications module 409. In some examples, processor 402 is configured to determine a first initiation point from a plurality of initiation points and/or perform LBT to contend for a COT starting at the first initiation point, e.g., by coordinating with COT module 408.

In an aspect, the UE 400 may include multiple transceivers 410 implementing different RATs (e.g., NR and LTE). In an aspect, the UE 400 may include a single transceiver 410 implementing multiple RATs (e.g., NR and LTE). In an aspect, the transceiver 410 may include various components, where different combinations of the components may implement different RATs.

Fig. 5 is a block diagram of an example BS500 in accordance with one or more aspects of the present disclosure. The BS500 may be the BS 105 in the network 100 as discussed above in fig. 1. As shown, BS500 may include a processor 502, a memory 504, a transceiver 510 including a modem subsystem 512 and an RF unit 514, and one or more antennas 516. These elements may communicate with each other, directly or indirectly, for example, via one or more buses.

The processor 502 may have various features that are special type processors. For example, these features may include a CPU, DSP, ASIC, controller, FPGA device, another hardware device, firmware device, or any combination thereof configured to perform the operations described herein. The processor 502 may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

The memory 504 may include cache memory (e.g., cache memory of the processor 502), RAM, MRAM, ROM, PROM, EPROM, EEPROM, flash memory, a solid state memory device, one or more hard drives, an array based on memristors, other forms of volatile and non-volatile memory, or a combination of different types of memory. In some aspects, memory 504 may include non-transitory computer-readable media. The memory 504 may store instructions 506. The instructions 506 may include instructions that, when executed by the processor 502, cause the processor 502 to perform the operations described herein (e.g., aspects of fig. 1). The instructions 506 may also be referred to as code, which may be broadly interpreted to include any type of computer-readable statements as discussed above with reference to FIG. 3.

As shown, transceiver 510 may include a modem subsystem 512 and an RF unit 514. Transceiver 510 may be configured to communicate bi-directionally with other devices, such as UE 115 and/or 300 and/or another core network element. Modem subsystem 512 may be configured to modulate and/or encode data according to an MCS (e.g., an LDPC coding scheme, a turbo coding scheme, a convolutional coding scheme, a digital beamforming scheme, etc.). The RF unit 514 may be configured to process (e.g., perform analog-to-digital conversion, digital-to-analog conversion, etc.) modulated/encoded data (e.g., sidelink resource configuration, sidelink COT sharing configuration) from a transmission from the modem subsystem 512 (on an outgoing transmission) or originating from another source, such as the UE 115, 215, 315, or 300. The RF unit 514 may be further configured to perform analog beamforming in conjunction with digital beamforming. Although shown as being integrated together in transceiver 510, modem subsystem 512 and/or RF unit 514 may be separate devices that are coupled together at BS 105 to enable BS 105 to communicate with other devices.

RF unit 514 may provide modulated and/or processed data, such as data packets (or more generally data messages that may contain one or more data packets and other information), to antenna 516 for transmission to one or more other devices. This may include, for example, information transfer to complete the attachment to the network and communication with the camped UE 115 or 300 in accordance with some aspects of the present disclosure. The antenna 516 may further receive data messages transmitted from other devices and provide the received data messages for processing and/or demodulation at the transceiver 510. Transceiver 510 may provide the demodulated and decoded data to any module of BS500 for processing. The antenna 516 may include multiple antennas of similar or different designs in order to maintain multiple transmission links.

In an aspect, BS500 may include multiple transceivers 510 implementing different RATs (e.g., NR and LTE). In an aspect, BS500 may include a single transceiver 510 implementing multiple RATs (e.g., NR and LTE). In an aspect, the transceiver 510 may include various components, where different combinations of the components may implement different RATs.

Fig. 6 illustrates a sidelink timeslot structure scheme 600 for sidelink transmissions in accordance with one or more aspects of the present disclosure. Scheme 600 may be employed by a UE 115 in a network, such as network 100. The network may support multiple starting points for sidelink transmission between the sidelink UEs. The x-axis represents time in some arbitrary units and the y-axis represents frequency in some arbitrary units.

In the example illustrated in fig. 6, the frequency band 602 may be a shared radio band or an unlicensed band shared by multiple network operating entities. The frequency band 602 may, for example, have a BW of about 10MHz or about 20MHz and a SCS of about 15kHz, about 30kHz, or about 60kHz. Frequency band 602 may be located at any suitable frequency. In some aspects, frequency band 602 may be located at approximately 2.5GHz, 6GHz, or 20 GHz.

UE 115 may communicate with one or more other UEs on a sidelink link using sidelink slot structure scheme 600. For example, the UE 115 may transmit a sidelink transmission 604 in the frequency band 602 to the other side link UE in a time slot 608 immediately preceding the time slot 606. The first time slot immediately precedes the second time slot if the second time slot is subsequent to the first time slot and there are no other time slots between the first time slot and the second time slot. The sidelink transmission 604 may be a slot-based transmission that includes PSCCH/PSCCH but no PSFCH. Accordingly, the time slots 606, 608 may correspond to the time slot 202 in fig. 2 and may include multiple symbols. The duration of the time slots 606, 608 may span any suitable number of symbols (e.g., OFDM symbols). In some aspects, the duration of the time slots 606, 608 may correspond to one TTI, which may include approximately fourteen symbols.

Slot 606 may include fourteen symbols including symbol 612 and symbol 614. Symbol 612 immediately precedes symbol 614 and may be used to transmit the PSCCH/PSCCH. Symbol 614 is the last symbol of slot 606 and may be used by multiple UEs to perform LBT to obtain COT 610 for transmission in slot 608. Slot 608 may include fourteen symbols including a start symbol 616, a symbol 618, and a symbol 620. The start symbol 616 may immediately precede the symbol 618, and the symbol 618 may immediately precede the symbol 620. The start symbol 616 may be a repetition of symbol 618 and may include an Automatic Gain Control (AGC) symbol. UE 115 may transmit a sidelink transmission 604 that includes the PSCCH/PSCCH during symbols 616, 618, and 620.

A UE 115 may contend for a COT 610 in a frequency band 602 for sidelink communication with another UE on a sidelink, which frequency band 602 may be a shared radio frequency band and/or an unlicensed frequency band. To communicate sidelink transmissions 604 on frequency band 602, ue 115 may perform LBT to contend for COT 610 in frequency band 602. LBT may refer to a channel sensing mechanism used by a device (e.g., UE 115) to determine the presence of other signals in a channel prior to transmission and avoid collisions with other transmissions. The device may listen to the medium for a period of time.

The UE 115 may determine a number of starting points 630, 632, 634, 636, and 638 (offset values) before the start of the COT 610 that have been predefined. The plurality of starting points 630, 632, 634, 636, and 638 are within the last symbol 614 of the slot 606. Each of the plurality of initiation points 630, 632, 634, 636 and 638 may be spaced apart by an initiation point gap. The time slot 608 may begin at time T0 and the starting point gap may be, for example, 9 μ s. For example, start point 630 may be at times T0-36 μ s, start point 632 may be at times T0-27 μ s, start point 634 may be at times T0-18 μ s, start point 636 may be at times T0-9 μ s, and start point 638 may be at time T0, which time T0 is at the beginning of start symbol 616 of slot 608. As will be discussed further below, if the UE 115 selects the starting point 630, 632, 634, or 636, respectively, as the first starting point, the UE 115 may fill the gap between the starting point 630, 632, 634, or 636 and the start of the slot 608 with the CP extension. The OFDM transmission (e.g., sidelink transmission 604) may begin at the beginning of a symbol boundary (e.g., time T0). If the first start point occurs before the start of the symbol boundary, the UE 115 may transmit a CP extension until the start of the symbol boundary to prevent other nodes from accessing the channel. If the UE 115 selects the start point 638 as the first start point, the UE 115 may not need to transmit the sidelink communication with CP extension 604, as will be discussed further below. The plurality of starting points may be SCS based. For example, the number of starting points and/or the location of the starting points within the symbol 614 may be based on SCS. In some examples, the SCS is about 15kHz, about 30kHz, or about 60kHz.

The COT 610 may start at a first starting point of a plurality of starting points 630, 632, 634, 636, and 638 within the last symbol 614 of the slot 606, as discussed in various aspects of the present disclosure. For example, the UE 115 may initiate transmission of the sidelink transmission 604 at any one of a plurality of origination points 630, 632, 634, 636, and 638.

In some instances, the UE 115 may perform CAT4LBT during the last symbol 614 of the slot 606 in contention for the COT 610. If the CAT4LBT result is an LBT failure, the UE 115 may refrain from transmitting in the frequency band 602 for a period of time and may then perform CAT4LBT again. If the CAT4LBT result is LBT pass, the UE 115 may proceed to use COT 610 for sidelink communications and accordingly may transmit a sidelink transmission starting at the first starting point. The CAT4LBT that results in LBT passing may also be referred to as successful CAT4 LBT. The transmission of the sidelink transmission 604 is conditioned on a successful CAT4 LBT. The UE 115 starts performing CAT4LBT such that CAT4LBT is no later than the first starting point ready. Earlier CAT4LBT based on maximum CW size may be desirable.

In some examples, the UE 115 may select the first origination point from among the plurality of origination points 630, 632, 634, 636, and 638 in various ways. In some instances, the UE 115 may randomly select one of the five origination points 630, 632, 634, 636, and 638 to initiate transmission of the sidelink communications. In an example, the UE 115 may select the first starting point based on a random number implemented from the UE 115. In an example, UE 115 may select the first starting point based on a random function having a uniform distribution.

In some aspects, the UE 115 may select the starting point 630 as the first starting point and perform the CAT4LBT 626 during the gap duration 640 in the last symbol 614 of the slot 606. CAT4LBT may be based on the maximum CW size. UE 115 may determine a CP extension length based on a first duration 642 between a first start point 630 of COT 610 and a start symbol 616 of slot 608 immediately following slot 606, and may apply a CP extension 644 with the CP extension length to sidelink transmission 604. The CP extension length may be based on the starting point 630 and the last symbol 614 of the slot 606 may include a gap duration 640 and a first duration 642. Based on the CAT4LBT 626 result being an LBT pass, the UE 115 may transmit the sidelink transmission 604 with the CP extension 644, starting at start point 630.

In some aspects, the UE 115 may select the starting point 632 as the first starting point and perform CAT4LBT 628 during the gap duration 646 in the last symbol 614 of the slot 606. CAT4LBT may be based on the maximum CW size. UE 115 may determine a CP extension length based on a first duration 648 between a first start point 632 of COT 610 and a start symbol 616 of slot 608 immediately following slot 606, and may apply a CP extension 650 having the CP extension length to sidelink transmission 604. The CP extension length may be based on the starting point 632 and the last symbol 614 of the slot 606 may include the gap duration 646 and the first duration 648. Based on the CAT4LBT 628 result being an LBT pass, the UE 115 may transmit a sidelink transmission 604 with a CP extension 650, which begins at start point 632.

If the UE 115 selects the starting point 634 or 636, the UE 115 may perform similar actions discussed above for transmitting the sidelink transmission 604. If the UE 115 selects the start point 638 as the first start point and performs the CAT4LBT 680 during the gap duration 652 in the last symbol 614 of the slot 606, the UE 115 may not need to determine the CP extension length between the first start point 638 of the COT 610 and the start of the start symbol 616 of the slot 608 and/or apply CP extension with the CP extension length to the sidelink communications 604 because the CP extension would be zero. Accordingly, if CAT4LBT 680 results in LBT pass, the UE 115 may transmit a sidelink transmission 604 (without CP extension) starting at the start point 638.

Fig. 7 illustrates a sidelink timeslot structure scheme 700 for sidelink transmissions in accordance with one or more aspects of the present disclosure. Scheme 700 may be employed by a UE 115 in a network, such as network 100. The network may support multiple starting points for sidelink transmissions between sidelink UEs. The x-axis represents time in some arbitrary units and the y-axis represents frequency in some arbitrary units.

In the example illustrated in fig. 7, the frequency band 702 may be a shared radio band or an unlicensed frequency band shared by multiple network operating entities. The band 702 may, for example, have a BW of about 10MHz or about 20MHz and a SCS of about 15kHz, about 30kHz, or about 60kHz. Frequency band 702 may be located at any suitable frequency. In some aspects, frequency band 702 may be located at approximately 2.5GHz, 6GHz, or 20 GHz.

UE 115 may communicate with one or more other UEs on a sidelink using sidelink slot structure scheme 700. For example, UE 115 may communicate PSFCH communication 704 in time slot 706 to another side link UE in frequency band 702. The PSFCH communication 704 may be a slot-based communication during which the UE 115 may receive or transmit HARQ ACK/NACK feedback. Time slot 706 may correspond to time slot 202 in fig. 2 and may include multiple symbols. The duration of the time slot 706 may span any suitable number of symbols (e.g., OFDM symbols). In some aspects, the duration of the time slot 706 may correspond to one TTI, which may include approximately fourteen symbols.

Slot 706 may include fourteen symbols including symbol 712, symbol 714, symbol 716, symbol 718, and symbol 720. Symbol 712 immediately precedes symbol 714 and may be used to transmit the PSCCH/PSCCH. Symbol 714 may be referred to as a gap symbol, and at least a portion of symbol 714 may be used by multiple UEs to perform LBT to acquire COT 710 for communicating PSFCH communications 704 in time slot 706. Symbol 714 immediately precedes symbol 716, and symbol 716 can be a repetition of symbol 718. UE 115 may transmit a PSFCH communication 704 including a PSFCH during symbol 716 and symbol 718 immediately preceding symbol 720. Symbol 720 is the last symbol of slot 706 and may be a gap symbol used by multiple UEs to perform LBT to acquire the COT in the next slot for communicating communication signals in the COT.

The starting symbol (not shown) of slot 706 may be the first symbol "0" of slot 707, symbol "9"712 may be the tenth symbol from the starting symbol of slot 706, symbol "10"714 may be the eleventh symbol from the starting symbol of slot 706, symbol "11"716 may be the twelfth symbol from the starting symbol of slot 706, symbol "12"718 may be the thirteenth symbol from the starting symbol of slot 706, and symbol "13"720 may be the fourteenth symbol from the starting symbol of slot 706. Symbol 720 is the last symbol of slot 706 and may correspond to symbol 614 in fig. 6. For example, the plurality of start points 630, 632, 634, 636, and 638 may be within the last symbol 720 of the slot 706.

Additionally or alternatively, the structure of symbol 714 may be similar to the structure of symbol 614 in fig. 6 in terms of a plurality of starting points 630, 632, 634, 636, and 638, gap duration(s), first duration(s), and the UE 115 performing CAT4 LBT. In the example illustrated in fig. 7, the UE 115 may select the starting point 630 as the first starting point and perform CAT4LBT 626 during a gap duration 640 in symbol 714 after the psch transmission in slot 706. UE 115 may determine a CP extension length based on a first duration 642 between a first start point 630 of COT 710 and a start of a symbol 716 of slot 706, and may apply a CP extension 644 having the CP extension length to the PSFCH communication 704. The symbol 714 of the slot 706 may include a gap duration 640 and a first duration 642. Based on the CAT4LBT 626 result being an LBT pass, the UE 115 may transmit the PSFCH communication 704 with the CP extension 644, starting at start point 630.

If the UE 115 selects the starting point 632, 634, or 636 in fig. 7, the UE 115 may perform similar actions for transmitting the PSFCH communication 704 discussed above. If the UE 115 selects the start point 638 as the first start point in fig. 7 and performs CAT4LBT 680 during the gap duration 652 in symbol 714 of slot 706, it may not be necessary for the UE 115 to determine the CP extension length between the first start point 638 of the COT 710 and the start of symbol 716 of slot 708 and/or to apply CP extension with the CP extension length to the PSFCH communication 704 because the CP extension will be zero. In this example, if CAT4LBT 680 results in LBT pass, the UE 115 may transmit PSFCH communications 704 (without CP extensions) beginning at start point 638.

Fig. 8 illustrates a sidelink timeslot structure scheme 800 for sidelink transmission in accordance with one or more aspects of the present disclosure. Scheme 800 may be employed by a UE 115 in a network, such as network 100. The network may support multiple starting points for sidelink transmissions between sidelink UEs. The x-axis represents time in some arbitrary units and the y-axis represents frequency in some arbitrary units.

In the example illustrated in fig. 8, the frequency band 802 may be a shared radio band or an unlicensed band shared by multiple network operating entities. The band 802 may, for example, have a BW of about 10MHz or about 20MHz and a SCS of about 15kHz. Frequency band 802 may be located at any suitable frequency. In some aspects, frequency band 802 may be located at approximately 2.5GHz, 6GHz, or 20 GHz.

UE 115 may communicate with one or more other UEs on a sidelink link using sidelink slot structure scheme 800. For example, the UE 115 may transmit a sidelink transmission 804 in a time slot 808 immediately preceding a time slot 806 in the frequency band 802 to the other side link UE. Sidelink transmission 804 may be a slot-based transmission that includes PSCCH/PSCCH but no PSFCH. Additionally, the time slots 806, 808 may correspond to the time slot 202 in fig. 2 and may include multiple symbols. The duration of the time slots 806, 808 may span any suitable number of symbols (e.g., OFDM symbols). In some aspects, the duration of the time slots 806, 808 may correspond to one TTI, which may include approximately fourteen symbols.

Slot 806 may include fourteen symbols including symbol 812 and symbol 814. Symbol 812 immediately precedes symbol 814 and may be used to transmit the PSCCH/PSCCH. Symbol 814 is the last symbol of slot 806 and may be used by multiple UEs to perform LBT to obtain COT 810 for transmission in the next slot 808. Slot 808 may include fourteen symbols including a start symbol 816, a symbol 818, and a symbol 820. The start symbol 816 can include a first portion 815 and a second portion 817 of a complete symbol in time. In some examples, the first portion 815 can be a first half symbol of the start symbol 816 and the second portion 817 can be a second half symbol of the start symbol 816. A half symbol may refer to a full symbol at or about the midpoint in time. In other words, a half symbol may have a duration of one-half or about one-half of a full symbol. The start symbol 816 may immediately precede the symbol 818, and the symbol 818 may immediately precede the symbol 820. A second portion 817 of the start symbol 816 can be a repetition of the symbol 818 and can include AGC symbols. UE 115 may transmit sidelink transmission 804 including PSCCH/PSCCH during symbols 816, 818, and 820.

A UE 115 may contend for a COT 810 in a frequency band 802 for communicating with a sidelink of another UE on a sidelink, which frequency band 802 may be a shared radio band and/or an unlicensed band. To communicate sidelink transmissions 804 on frequency band 802, ue 115 may perform LBT to contend for COT 810 in frequency band 802.

The UE 115 may determine a number of starting points 830, 832, 834, 8230; and 838 (offset values) before the start of the COT 810 that have been predefined. The multiple starting points 830, 832, 834, 8230, and 838 are within the last symbol 814 of the slot 806 and within the first portion 815 of the starting symbol 816 of the slot 808. Thus, the multiple starting points 830, 832, 834, 8230 \8230 \ 8230:and 838 span both time slots 806 and 808.

Each of the plurality of starting points 830, 832, 834 \8230; and 838 may be spaced apart from one another by a starting point gap. A second portion 817 of the symbol 816 may begin at time T0 and the starting point gap may be, for example, 9 μ s. For example, the plurality of origins may include ten origins, wherein the origin 830 may be at times T0-81 μ s, the origin 832 may be at times T0-72 μ s, an origin (not shown) may be at times T0-63 μ s, an origin (not shown) may be at times T0-54 μ s, an origin (not shown) may be at times T0-45 μ s, an origin (not shown) may be at times T0-36 μ s, an origin (not shown) may be at times T0-27 μ s, an origin (not shown) may be at times T0-18 μ s, the origin 834 may be at times T0-9 μ s, and the origin 838 may be at time T0, which time T0 begins at the second portion 817 of the start symbol 816 of the slot 808.

An OFDM transmission (e.g., sidelink transmission 804) may begin at the beginning of a slot or mini-slot symbol boundary. As will be discussed further below, if the selected starting point occurs before the start symbol 816 of the time slot 808 (e.g., before the first portion 815 of the start symbol 816), the UE 115 may fill the gap between the selected starting point and the start of the first portion 815 with a CP extension. If the UE 115 passes LBT before the start of the mini-slot symbol boundary (e.g., time T0), the UE 115 may transmit a CP extension until the start of the symbol boundary to prevent other nodes from accessing the channel. Additionally or alternatively, the UE 115 may puncture a portion of the first portion 815 if the selected starting point occurs within the starting symbol 816 of the time slot 808 (e.g., within the first portion 815 of the starting symbol 816).

If the UE 115 selects the starting point 838 as the first starting point, the UE 115 may not have to transmit the sidelink communications 804 with the CP extension, as will be discussed further below. The plurality of starting points may be SCS based. For example, the number of starting points and/or the location of the starting points within symbols 814 and 816 may be based on SCS.

The COT 810 may begin at a first starting point of a plurality of starting points 830, 832, 834, 8230 \8230 \ 8230 \ 8230and 838 within the last symbol 814 and/or the first portion 815 of the starting symbol 816 of the time slot 806, as discussed in various aspects of the present disclosure. For example, the UE 115 may initiate transmission of the sidelink transmission 804 at any one of a plurality of origination points 830, 832, 834, 8230; and 838.

In some examples, the UE 115 may perform CAT4LBT to contend for the COT 810 during the last symbol 804 of the slot 806 and/or during the first portion 815 of the start symbol 816. If the CAT4LBT result is an LBT failure, the UE 115 may refrain from transmitting in the frequency band 802 for a period of time and then perform CAT4LBT again. If the CAT4LBT result is LBT pass, the UE 115 may proceed to use COT 810 for sidelink communications and accordingly may transmit a sidelink transmission starting at the first starting point. The transmission of the sidelink transmission 804 is conditioned on a successful CAT4 LBT. The UE 115 starts performing CAT4LBT such that CAT4LBT is no later than the first start point ready. Earlier CAT4LBT based on maximum CW size may be desirable.

In some examples, UE 115 may select the first starting point from a plurality of starting points 830, 832, 834, 8230, and 838 in various manners. In some examples, UE 115 may randomly select one of a plurality of starting points 830, 832, 834, 8230, and 838 to initiate transmission of the sidelink communications. In an example, the UE 115 may select the first starting point based on a random number implemented from the UE 115. In an example, the UE 115 may select the first starting point based on a configuration of the UE 115.

In some aspects, the UE 115 may select the starting point 830 as the first starting point and perform CAT4LBT 826, which CAT4LBT 826 may be completed no later than the first starting point if the channel is empty. The starting point 830 occurs before the start of the starting symbol 816 of the slot 808, and the UE 115 may pass through the CAT4LBT 826 before the start of the starting symbol 816 of the slot 808. Accordingly, UE 115 may determine a CP extension length based on a first duration 842 between a first start point 830 of COT 810 and a start (e.g., symbol boundary) of a start symbol 816 of slot 808 immediately following slot 806, and may apply a CP extension 844 having the CP extension length to sidelink transmissions 804. Based on the first start point 830 occurring before the start of the start symbol 816 of the time slot 808, the UE 115 may transmit the sidelink transmission 804 with the CP extension 844, the transmission beginning at the start point 830. CP extension 844 may be a CP extension of AGC symbol 816. If the UE 115 selects a starting point that occurs before the start of the start symbol 816 of the slot 808 and/or the UE 115 passes through CAT4LBT before the start of the start symbol 816 of the slot 808, the UE 115 may perform similar actions for transmitting the sidelink transmission 804 discussed above.

In some aspects, the UE 115 may select the starting point 834 as the first starting point and perform CAT4LBT 835, which CAT4LBT 835 may be completed no later than the first starting point if the channel is empty. The starting point 834 occurs after the start of the starting symbol 816 of the slot 808, and the UE 115 may pass through the CAT4LBT 826 after the start of the starting symbol 816 of the slot 808. Accordingly, UE 115 may puncture the portion between the start of start symbol 816 up to the start of symbol portion 882. Symbol portion 882 and a second portion 817 of start symbol 816 can include a partial AGC symbol, and first portion 815 can immediately precede the partial AGC symbol. The AGC symbols can be punctured such that the remaining portion (e.g., the partial AGC symbols) is long enough (e.g., at least 30 μ s) for AGC purposes. The minimum portion of the AGC symbol may depend on the UE capability. Based on the first start point occurring after the start of the starting symbol 816 of the slot 808, the UE 115 may puncture a portion of the first portion 815 and transmit the sidelink transmission 804 beginning at the start point 834. If the UE 115 selects a starting point that occurs within the start of the start symbol 816 of the slot 808 and/or the UE 115 passes through CAT4LBT after the start of the start symbol 816 of the slot 808, the UE 115 may perform similar actions discussed above for transmitting the sidelink transmission 804.

If UE 115 selects starting point 838 as the first starting point in fig. 8 and performs CAT4LBT 880 during gap duration 852 in symbol 814 and first portion 815 of symbol 816 of slot 806, UE 115 may not need to determine the CP extension length between the first starting point 838 of COT 810 and symbol 816 because the CP extension would be zero. The UE 115 may puncture the first portion 815 (e.g., the portion between the beginning of the punctured symbol 816 and the beginning of the second portion 817 of the symbol 816).

Fig. 9 illustrates a sidelink timeslot structure scheme 900 for sidelink transmission in accordance with one or more aspects of the present disclosure. Scheme 900 may be employed by a UE 115 in a network, such as network 100. The network may support multiple starting points for sidelink transmissions between sidelink UEs. The x-axis represents time in some arbitrary units and the y-axis represents frequency in some arbitrary units.

In the example illustrated in fig. 9, the frequency band 902 may be a shared radio band or an unlicensed frequency band shared by multiple network operating entities. Band 902 may, for example, have a BW of about 10MHz or about 20MHz and a SCS of about 15kHz. Band 902 may be located at any suitable frequency. In some aspects, frequency band 902 may be located at approximately 2.5GHz, 6GHz, or 20 GHz.

UE 115 may communicate with one or more other UEs on a sidelink using sidelink slot structure scheme 900. For example, the UE 115 may communicate the PSFCH communication 904 in time slot 906 to the other side link UE in frequency band 902. The PSFCH communication 904 may be a slot-based communication during which the UE 115 may receive or transmit HARQ ACK/NACK feedback. Time slot 906 may correspond to time slot 202 in fig. 2 and may include multiple symbols. The duration of time slot 906 may span any suitable number of symbols (e.g., OFDM symbols). In some aspects, the duration of the time slot 906 may correspond to one TTI, which may include approximately fourteen symbols.

Slot 906 may include fourteen symbols including symbol 912, symbol 914, symbol 916, symbol 918, and symbol 920. Symbol 912 immediately precedes symbol 914 and may be used to transmit the PSCCH/PSCCH. Symbol 914 may be referred to as a gap symbol, and at least a portion of symbol 914 may be used by multiple UEs to perform LBT to acquire COT 910 for communicating PSFCH communications 904 in time slot 906. Symbol 914 immediately precedes symbol 916, and a second portion 917 of symbol 916 may be a repetition of symbol 918. The UE 115 may transmit a PSFCH communication 904 including the PSFCH during a second portion 917 of the symbol 916 and a symbol 918 immediately preceding the symbol 920. Symbol 920 is the last symbol of slot 906 and may be a gap symbol used by multiple UEs to perform LBT to obtain the COT in the next slot for communicating communication signals in the COT.

A starting symbol (not shown) of the slot 906 may be the first symbol "0" of the slot 906, symbol "9"912 may be the tenth symbol from the starting symbol of the slot 906, symbol "10"914 may be the eleventh symbol from the starting symbol of the slot 906, symbol "11"916 may be the twelfth symbol from the starting symbol of the slot 906, symbol "12"918 may be the thirteenth symbol from the starting symbol of the slot 906, and symbol "13"920 may be the fourteenth symbol from the starting symbol of the slot 906. Symbol 920 is the last symbol of slot 906 and may correspond to symbol 814 in fig. 8. For example, multiple starting points 830, 832, 834, \8230 \ 8230;, and 838 may be within the last symbol 920 of the slot 906.

Additionally or alternatively, the structure of symbols 914 and 916 may be similar to the structure of symbols 814 and 816 in fig. 8 in terms of a plurality of starting points 830, 832, 834 \8230, 8230, and 838, gap duration(s), first duration(s), and the UE 115 performing CAT4 LBT. In the example illustrated in fig. 9, the UE 115 may select the starting point 830 as the first starting point and perform CAT4LBT 826, which CAT4LBT 826 may complete no later than the first starting point if the channel is empty. The starting point 830 occurs before the start of the symbol 916 of the slot 906, and the UE 115 may pass through the CAT4LBT 826 before the start of the symbol 916 of the slot 906. Accordingly, UE 115 may determine the CP extension length based on a first duration 842 between a start point 830 of COT 910 and a beginning of a symbol 916 (e.g., a symbol boundary) of slot 906. The UE 115 may apply a CP extension 844 having a CP extension length to the PSFCH communication 904. The CP extension length may be based on the starting point 830, and the symbol 914 and the first portion 915 of the symbol 916 of the slot 906 may include the gap duration 840 and the first duration 842. Based on the first start point 830 occurring before the start of the symbol 916 of the slot 906, the UE 115 may transmit the PSFCH communication 904 with the CP extension 844, the transmission beginning at the start point 830. CP extension 844 may be a CP extension of AGC symbol 916. If the UE 115 selects a starting point in fig. 9 that occurs before the start of symbol 916 of slot 906 and/or the UE 115 passes CAT4LBT before the start of symbol 916 of slot 906, the UE 115 may perform similar actions discussed above for transmitting the PSFCH communication 904.

In some aspects, the UE 115 may select the starting point 834 as the first starting point and perform CAT4LBT 835, which CAT4LBT 835 may be completed no later than the first starting point if the channel is empty. The starting point 834 occurs after the start of symbol 916 of slot 906, and the UE 115 may pass through CAT4LBT 835 after the start of symbol 916 of slot 906. Accordingly, the UE 115 may puncture the first portion 915 of the symbol 916. The second portion 917 of the symbol 916 may comprise a partial AGC symbol, and the first portion 915 may immediately precede the partial AGC symbol. The portion of the AGC symbol may be at least 30 mus. Based on the CAT4LBT 835 resulting in an LBT pass after the start of the symbol 916 of the slot 906, the UE 115 may puncture a portion of the first portion 915 of the symbol 916 and communicate the PSFCH communication 904, the communication beginning at start point 834. For example, the UE 115 may puncture the portion between the start of the symbol 916 up to the start of the symbol portion 982. If the UE 115 selects a starting point to occur within the start of symbol 916 of slot 906 and/or the UE 115 passes CAT4LBT after the start of symbol 916 of slot 906, the UE 115 may perform similar actions discussed above for transmitting the PSFCH communication 904.

If UE 115 selects starting point 838 as the first starting point in fig. 9 and performs CAT4LBT 880 during gap duration 852 in symbol 914 and first portion 915 of symbol 916 of slot 906, UE 115 may not need to determine the CP extension length between first starting point 838 of COT 910 and second portion 917 of symbol 916 because the CP extension would be zero. The UE 115 may puncture the first portion 915 (e.g., the portion between the beginning of the punctured symbol 916 up to the beginning of the second portion 917 of the symbol 916).

In some aspects, the multiple starting points may be a function of whether the UE 115 will use full BW or partial BW to transmit the side link communications (e.g., depending on the amount of data used for the side link transmission). A first set of the plurality of startpoints can be associated with the UE 115 occupying a full bandwidth, and a single startpoint of the plurality of startpoints can be associated with the UE 115 occupying a portion of the full bandwidth. The partial BW may be frequency interleaved (spaced RBs) or a group of contiguous RBs.

In some examples, each starting point of the first set of starting points occurs before the single starting point, and the UE 115 may perform LBT in the full bandwidth if the first starting point is within the first set of starting points and may perform LBT in a partial bandwidth of the full bandwidth if the first starting point is not present in the first set of starting points. In some examples, each starting point of the first set of starting points occurs after the single starting point, and the UE 115 may perform LBT in the full bandwidth if the first starting point is within the first set of starting points and may perform LBT in a partial bandwidth of the full bandwidth if the first starting point is not present in the first set of starting points. In some examples, the single starting point is time-varying, and the UE 115 may perform LBT in the full bandwidth if the first starting point is within the first set of starting points and may perform LBT in a partial bandwidth of the full bandwidth if the first starting point is not present in the first set of starting points.

Fig. 10 illustrates a flow diagram of a communication method 1000 for communicating side-link communications in accordance with one or more aspects of the present disclosure. The blocks of method 1000 may be performed by a computing device (e.g., a processor, processing circuitry, and/or other suitable components) of a wireless communication device. In some aspects, the wireless communication device is a UE (e.g., UE 115 and/or UE 400) that may perform the blocks of method 1000 with one or more components, such as processor 402, memory 404, COT module 408, sidelink communication module 409, transceiver 410, and/or antenna 416. Method 1000 may employ aspects similar to transmission frame structure 200 in fig. 2, CAT4LBT scheme 300 in fig. 3, sidelink timeslot structure scheme 600 in fig. 6, sidelink timeslot structure scheme 700 in fig. 7, sidelink timeslot structure scheme 800 in fig. 8, and/or sidelink timeslot structure scheme 900 in fig. 9. As illustrated, method 1000 includes several enumerated blocks, although aspects of method 1000 may include additional blocks before, after, and/or between these enumerated blocks. In some aspects, one or more of the enumerated blocks may be omitted or performed in a different order.

At block 1010, the method 1000 includes determining a first starting point from a plurality of starting points. In an example, UE 115 or UE 400 determines (e.g., via processor 402) a first starting point from a plurality of starting points. The plurality of starting points may be pre-configured. In some examples, the multiple starting points can span one full symbol (e.g., symbol 614 in fig. 6 and symbol 714 in fig. 7). In some examples, the multiple starting points can span one full symbol and a portion of the second symbol (e.g., symbol 814 and first portion 815 of symbol 816 in fig. 8 and symbol 914 and first portion 915 of symbol 916 in fig. 9). UE 115 or UE 400 (e.g., via processor 402) may randomly select a first starting point among the configured plurality of starting points based on a uniform distribution function. The plurality of starting points may be based on SCS, which may be, for example, about 15kHz, about 30kHz, or about 60kHz.

In some aspects, a first duration between at least two of the plurality of start points may be 9 μ β, and the plurality of start points may occur before the COT starting at the first start point. In some aspects, the first duration between the first start point and each of the plurality of start points is a multiple of 9 μ β, and the plurality of start points may occur before the COT starting at the first start point.

At block 1020, method 1000 includes performing LBT to contend for a COT starting at a first starting point. In an example, UE 115 or UE 400 performs LBT (e.g., via processor 402) to contend for a COT starting at a first starting point. The LBT may be CAT4LBT as discussed with respect to, for example, aspects of fig. 3. CAT4LBT may be based on the maximum contention window size.

At block 1030, the method 1000 includes transmitting a sidelink communication beginning at a first starting point during a COT based on the LBT. In an example, UE 115 or UE 400 transmits (e.g., via processor 410) a sidelink communication beginning at a first starting point during a COT based on LBT. The transmission of the sidelink transmission 604 is conditioned on a successful CAT4 LBT. For example, if the CAT4LBT result is an LBT failure, the UE 115 may refrain from transmitting in the frequency band for a period of time and may then perform CAT4LBT again. If the CAT4LBT result is an LBT pass, the UE 115 may proceed to use COT for sidelink communications and accordingly may transmit a sidelink transmission starting at the first starting point. In some examples, the sidelink transmission is devoid of PSFCH. In some examples, UE 115 or UE 400 transmits a sidelink transmission that includes the PSSCH. UE 115 or UE 400 may transmit a sidelink transmission with CP extension. The CP extension length may be based on the first starting point.

In some aspects, UE 115 or UE 400 may perform LBT during the last symbol of the first slot. In some examples, the plurality of start points are entirely within the last symbol of the first time slot, and UE 115 or UE 400 may determine the CP extension length based on a first duration between the first start point of the COT and a start symbol of a second time slot immediately following the first time slot. UE 115 or UE 400 may apply CP extension with a CP extension length to sidelink transmissions and transmit the sidelink transmissions with the CP extension. In some examples, UE 115 or UE 400 may perform LBT during a gap duration in a last symbol of the first slot, and the last symbol of the first slot includes the gap duration and the first duration. UE 115 or UE 400 may transmit a sidelink transmission with a CP extension during the first duration.

In some examples, the plurality of starting points are within a last symbol of the first slot and a first portion of a starting symbol of the second slot. For example, the plurality of starting points may span two adjacent symbols. UE 115 or UE 400 (e.g., via processor 402) may puncture a first portion of a start symbol of a second slot. The second portion of the start symbol may include an AGC symbol, and the first portion may immediately precede the AGC symbol.

In some aspects, UE 115 or UE 400 may perform LBT (e.g., via processor 402) during a first symbol after a PSSCH transmission in a slot. UE 115 or UE 400 may determine the CP extension length based on a first duration between a first starting point of the COT and a second symbol of the slot immediately following the first symbol. The UE 115 or the UE 400 may apply the CP extension having the CP extension length to the sidelink transmission and transmit the sidelink transmission with the CP extension. UE 115 or UE 400 (e.g., via transceiver 410) may communicate the PSFCH during a third symbol of the slot, where the third symbol is between the second symbol and the last symbol in the slot. For example, the third symbol may immediately follow the second symbol in the slot and immediately precede the last symbol in the slot.

In some aspects, UE 115 or UE 400 (e.g., via processor 702) may perform LBT during a first symbol following a pscch transmission in a slot and during a first portion of a second symbol immediately following the first symbol. UE 115 or UE 400 may puncture the first portion of the second symbol if the first starting point occurs within the first portion of the second symbol. The second portion of the second symbol may comprise an AGC symbol, and the first portion may immediately precede the AGC symbol. UE 115 or UE 400 (e.g., via transceiver 410) may communicate the PSFCH during a third symbol of the time slot, where the third symbol is between the second symbol and the last symbol in the time slot. The third symbol may immediately follow the second symbol in the slot and immediately precede the last symbol in the slot. The multiple starting points may be based on SCS, e.g. 15kHz.

Fig. 11 illustrates a flow diagram of a communication method 1100 for communicating sidelink communications in accordance with one or more aspects of the present disclosure. The blocks of method 1100 may be performed by a computing device (e.g., a processor, processing circuitry, and/or other suitable components) of a wireless communication device. In some aspects, the wireless communication device is a UE (e.g., UE 115 and/or UE 400) that may perform the blocks of method 1000 with one or more components, such as processor 402, memory 404, COT module 408, sidelink communication module 409, transceiver 410, and/or antenna 416. Method 1100 may employ aspects similar to transmission frame structure 200 in fig. 2, CAT4LBT scheme 300 in fig. 3, sidelink timeslot structure scheme 600 in fig. 6, sidelink timeslot structure scheme 700 in fig. 7, sidelink timeslot structure scheme 800 in fig. 8, and/or sidelink timeslot structure scheme 900 in fig. 9. As illustrated, method 1100 includes several enumerated blocks, although aspects of method 1100 may include additional blocks before, after, and/or between these enumerated blocks. In some aspects, one or more of the enumerated blocks may be omitted or performed in a different order.

At block 1110, the method 1100 includes determining a first starting point from a plurality of starting points. In an example, UE 115 or UE 400 determines (e.g., via processor 402) a first starting point from a plurality of starting points. The plurality of starting points may be preconfigured. In some examples, the multiple starting points can span one full symbol (e.g., symbol 614 in fig. 6 and symbol 714 in fig. 7). In some examples, the multiple starting points can span one full symbol and a portion of a second symbol (e.g., symbol 814 and first portion 815 of symbol 816 in fig. 8 and symbol 914 and first portion 915 of symbol 916 in fig. 9). UE 115 or UE 400 (e.g., via processor 402) may randomly select a first starting point among the configured plurality of starting points based on a uniform distribution function. The multiple starting points may be based on SCS, which may be, for example, about 15kHz, about 30kHz, or about 60kHz.

At block 1115, the method 1100 includes performing listen before talk contention for a Channel Occupancy Time (COT) starting at a first starting point. In an example, UE 115 or UE 400 performs LBT (e.g., via processor 402) to contend for a COT that starts at a first starting point. The LBT may be CAT4LBT as discussed with respect to, for example, aspects of fig. 3. The CAT4LBT may be based on the maximum contention window size.

At block 1120, the method 1100 includes determining whether the first starting point is within a symbol that includes an Automatic Gain Control (AGC) symbol. In an example, UE 115 or UE 400 (e.g., via processor 402) may determine whether the first starting point is within a symbol that includes AGC symbols.

From block 1120, the process flow may proceed to block 1130 if the first starting point is within a symbol that includes an AGC symbol. At block 1130, the method 1100 includes puncturing a first portion of the symbol, a second portion of the symbol including an AGC symbol and immediately following the first portion. In an example, UE 115 or UE 400 (e.g., via processor 402) may puncture a first portion of the symbol, a second portion of the symbol comprising and immediately following the AGC symbol. At block 1140, the method 1100 includes transmitting a sidelink communication beginning at a first start point during the COT. In an example, UE 115 or UE 400 transmits (e.g., via transceiver 410) a sidelink communication during the COT that begins at a first starting point.

From block 1120, the process flow may proceed to block 1150 if the first starting point is not within a symbol that includes an AGC symbol. At block 1150, the method 1100 includes determining a Cyclic Prefix (CP) extension length based on a first duration between a first start point of the COT and a start of the symbol. In an example, UE 115 or UE 400 (e.g., via processor 402) may determine the CP extension length based on a first duration between a first start point of the COT and a start of the symbol. For example, UE 115 or UE 400 may determine the CP extension length in connection with, for example, aspects of fig. 6-9.

At block 1160, method 1100 includes applying a CP extension having a CP extension length to the sidelink communications. In an example, UE 115 or UE 400 (e.g., via processor 402) may apply a CP extension having a CP extension length to sidelink communications. For example, UE 115 or UE 400 may apply CP extension with a CP extension length to sidelink communications in conjunction with, for example, the aspects of fig. 6-9. At block 1170, method 1100 includes transmitting side link communications with CP extensions during the COT, the transmitting beginning at a first starting point. In an example, UE 115 or UE 400 (e.g., via transceiver 410) may transmit a sidelink communication with CP extension during the COT, the transmission starting at a first starting point.

Information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

The various illustrative blocks and modules described in connection with the disclosure herein may be implemented or performed with a general purpose processor, a DSP, an ASIC, an FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration).

The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Other examples and implementations are within the scope of the disclosure and the following claims. For example, due to the nature of software, the functions described above may be implemented using software executed by a processor, hardware, firmware, hard-wired, or any combination thereof. Features that perform a function may also be physically located at various positions, including being distributed such that portions of the function are performed at different physical locations. In addition, as used herein, including in the claims, "or" as used in a list of items (e.g., a list of items accompanied by a phrase such as "at least one of" or "one or more of") indicates an inclusive list, such that, for example, a list of [ at least one of a, B, or C ] means a or B or C or AB or AC or BC or ABC (i.e., a and B and C).

As those of ordinary skill in the art will appreciate so far and depending on the particular application at hand, many modifications, substitutions, and variations may be made in the materials, devices, configurations, and methods of use of the apparatus of the present disclosure without departing from the spirit and scope of the present disclosure. In view of the above, the scope of the present disclosure should not be limited to the particular embodiments illustrated and described herein (as they are merely some examples of the disclosure), but rather should be fully commensurate with the appended claims and their functional equivalents.

Claims (40)

1. A method of performing wireless communication by a User Equipment (UE), comprising:

determining a first starting point from a plurality of starting points;

performing Listen Before Talk (LBT) to contend for a Channel Occupancy Time (COT) starting at the first starting point; and

transmitting, during the COT, a sidelink communication beginning at the first starting point based on the LBT.

2. The method performed by the UE of claim 1, wherein performing the LBT comprises performing the LBT during a last symbol of a first slot, the method further comprising:

determining a Cyclic Prefix (CP) extension length based on a first duration between the first start point of the COT and a start symbol of a second slot immediately following the first slot; and

applying a CP extension having the CP extension length to the sidelink communications, wherein transmitting the sidelink communications comprises transmitting the sidelink communications with the CP extension.

3. The method of claim 2, wherein the plurality of starting points are within the last symbol of the first slot.

4. The method of claim 3, wherein the plurality of starting points are based on subcarrier spacing (SCS).

5. The method of claim 4, wherein the SCS is 15kHz, 30kHz or 60kHz.

6. The method of claim 3, wherein performing the LBT comprises performing the LBT during a gap duration in the last symbol of the first slot, and the last symbol of the first slot comprises the gap duration and the first duration, and wherein transmitting the sidelink communication with the CP extension comprises transmitting the CP extension during the first duration.

7. The method of claim 2, wherein the plurality of starting points are within a first portion of the start symbol of the second slot.

8. The method of claim 7, wherein the first starting point occurs within the starting symbol of the second slot.

9. The method performed by the UE of claim 8, further comprising:

puncturing the first portion of the start symbol of the second slot, the second portion of the start symbol comprising an Automatic Gain Control (AGC) symbol and the first portion immediately preceding the AGC symbol.

10. The method of claim 2, wherein the sidelink communications are free of a Physical Sidelink Feedback Channel (PSFCH).

11. The method of claim 2, wherein transmitting the sidelink communication with the CP extension comprises transmitting a physical sidelink shared channel (psch).

12. The method of claim 2, wherein the CP extension length is based on the first starting point.

13. The method performed by the UE of claim 1, wherein performing the LBT comprises performing the LBT during a first symbol after PSSCH transmission in a slot, the method further comprising:

determining a CP extension length based on a first duration between the first start point of the COT and a second symbol of the slot immediately following the first symbol; and

applying a CP extension having the CP extension length to the sidelink communications, wherein transmitting the sidelink communications comprises transmitting the sidelink communications with the CP extension.

14. The method performed by the UE of claim 13, further comprising:

communicating a PSFCH during a third symbol of the slot, the third symbol being between the second and last symbols in the slot.

15. The method of claim 14, wherein the third symbol immediately follows the second symbol in the slot and immediately precedes the last symbol in the slot.

16. The method of claim 13, wherein the plurality of starting points are based on SCS, and the SCS is 15kHz, 30kHz, or 60kHz.

17. The method performed by the UE of claim 1, wherein performing the LBT comprises performing the LBT during a first symbol following a PSSCH transmission in a slot and during a first portion of a second symbol immediately following the first symbol, and the first starting point occurs within the first portion of the second symbol, the method further comprising:

puncturing the first portion of the second symbol, the second portion of the second symbol comprising an AGC symbol and the first portion immediately preceding the AGC symbol.

18. The method performed by the UE of claim 17, further comprising:

communicating a PSFCH during a third symbol of the slot, the third symbol being between the second and last symbols in the slot.

19. The method of claim 18, wherein the third symbol immediately follows the second symbol in the slot and immediately precedes the last symbol in the slot.

20. The method of claim 19, wherein the plurality of starting points are based on SCS, and the SCS is 15kHz.

21. The method of claim 1, wherein a first set of the plurality of starting points is associated with the UE occupying a full bandwidth and a single starting point of the plurality of starting points is associated with the UE occupying a partial bandwidth of the full bandwidth.

22. The method of claim 21, wherein each starting point of the first set of starting points occurs before the single starting point, wherein performing the LBT comprises performing the LBT in the full bandwidth if the first starting point is within the first set of starting points, and wherein performing the LBT comprises performing the LBT in the partial bandwidth of the full bandwidth if the first starting point is not present in the first set of starting points.

23. The method of claim 21, wherein each starting point of the first set of starting points occurs after the single starting point, wherein performing the LBT comprises performing the LBT in the full bandwidth if the first starting point is within the first set of starting points, and wherein performing the LBT comprises performing the LBT in the portion of the full bandwidth if the first starting point is not present in the first set of starting points.

24. The method of claim 21, wherein the single start point is time-varying, wherein performing the LBT comprises performing the LBT in the full bandwidth if the first start point is within the first set of start points, and wherein performing the LBT comprises performing the LBT in the partial bandwidth of the full bandwidth if the first start point is not present in the first set of start points.

25. The method of claim 1, wherein a first duration between at least two of the plurality of start points is 9 μ β and the plurality of start points occur before the COT starting at the first start point.

26. The method of claim 1, wherein a first duration between a first start point and each of the plurality of start points is a multiple of 9 μ β, and the plurality of start points occur before the COT that starts at the first start point.

27. The method performed by the UE of claim 1, wherein determining the first starting point comprises:

selecting the first starting point based on a random selection.

28. The method of claim 1, wherein transmitting the COT comprises transmitting the COT if the LBT result is an LBT pass.

29. The method of claim 1, wherein the LBT is a category 4LBT (CAT 4 LBT) based on a maximum contention window size.

30. A User Equipment (UE), comprising:

a processor configured to:

determining a first starting point from a plurality of starting points; and

performing Listen Before Talk (LBT) to contend for a Channel Occupancy Time (COT) starting at the first starting point; and

a transceiver configured to transmit a sidelink communication beginning at the first starting point during the COT based on the LBT.

31. The UE according to claim 30, wherein the UE is further configured to,

wherein the processor is configured to:

performing the LBT during a last symbol of a first slot;

determining a Cyclic Prefix (CP) extension length based on a first duration between the first start point of the COT and a start symbol of a second slot immediately following the first slot; and

applying a CP extension having the CP extension length to the sidelink communications; and wherein the transceiver is configured to transmit the sidelink communications with the CP extension.

32. The UE of claim 31, wherein the plurality of starting points are within the last symbol of the first slot.

33. A non-transitory computer-readable medium having program code recorded thereon, the program code comprising:

code for causing a sidelink User Equipment (UE) to determine a first starting point from a plurality of starting points;

code for causing the side link UE to perform Listen Before Talk (LBT) to contend for a Channel Occupancy Time (COT) starting at the first starting point; and

code for causing the side link UE to transmit a side link communication beginning at the first starting point during the COT based on the LBT.

34. The non-transitory computer-readable medium of claim 33, wherein the code for causing the UE to perform the LBT comprises code for causing the UE to perform the LBT during a first symbol after a psch transmission in a slot.

35. The non-transitory computer-readable medium of claim 34, the program code further comprising:

code for causing the side link UE to determine a CP extension length based on a first duration between the first start point of the COT and a second symbol of the time slot immediately following the first symbol; and

code for causing the side-link UE to apply a CP extension having the CP extension length to the side-link communication, wherein the code for causing the UE to transmit the side-link communication comprises code for causing the UE to transmit the side-link communication with the CP extension.

36. The non-transitory computer-readable medium of claim 35, the program code further comprising:

code for causing the sidelink UE to communicate PSFCH during a third symbol of the time slot, wherein the third symbol immediately follows the second symbol in the time slot and immediately precedes a last symbol in the time slot.

37. A User Equipment (UE), comprising:

means for determining a first starting point from a plurality of starting points;

means for performing Listen Before Talk (LBT) to contend for a Channel Occupancy Time (COT) starting at the first start point; and

means for transmitting a sidelink communication during the COT beginning at the first starting point based on the LBT.

38. The UE of claim 37, wherein the means for performing the LBT comprises means for performing the LBT during a first symbol after a psch transmission in a slot and during a first portion of a second symbol immediately after the first symbol, and wherein the first start point occurs within the first portion of the second symbol.

39. The UE of claim 38, further comprising:

means for puncturing the first portion of the second symbol, the second portion of the second symbol comprising an AGC symbol and the first portion immediately preceding the AGC symbol.

40. The UE of claim 39, further comprising:

means for communicating a PSFCH during a third symbol of the slot, the third symbol being between the second symbol and a last symbol in the slot.

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